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UPDATE
After talking with ARGlaser about my gun sight issue we decided the use of nichrome wire could possibly work in heating a DPSS Green in the cold. I have decided to change the thread topic from "help with my gun sight" to research into using nichrome wire. I will be posting every test/experiment I do with trying to make it work!!! Wish me luck and I would like to hear everyones opinion about what I am trying to do.

I found this site for anyone who ever thought about using nichrome it helps to determine what temperature a certain setup will create.

Ok guys i am in need of your help with my green vs cold issue. I have searched the forum and have seen multiple ways people have kept their dpss warm in the cold but nothing seems to fit my exact situation. I have made an 80mw green rifle site and it actually works great. I have it mounted on my 22 just for fun right now and it pretty i am very pleased with its performance. What I have done was purchased a $25 red laser scope from china and pretty much just swapped the module with a green, i only had to do a little modifying to make it work. The good part is it's cheap and works great, the bad part is in the cold it only works for a couple minutes before i need to go warm it up inside again

__________________ARGMeterw/ Ophir

Last edited by mhemling33; 03-16-2013 at 03:43 AM.
Reason: Shift in thread topic

I just got a 520 but I was trying to find a way to make it work with the cheap dpss 532nm though. I have had some progress with it but I haven't had alot of time to mess with it. You have to first put heatshrink over the module or some type of non conductive barrier, I had placed a module in the freezer overnight already wrapped in nichrome wire. the next day I applied power to the module right out of the freezer and nothing then I sent 3.7V through the nichrome wire for about 15seconds and tried it out again and it was working. The temperatures have become to warm where I live to really test this idea out. So this means i will have to continue next fall.

Well, i have experience using nichrome wire in my ecig. I have several juice tanks that use a coil of nichrome wrapped around silica wick. IIRC, the higher the guage, the lower the resistance per foot. I would say try getting the thinnest possible, and wrap alot around. Since you are basically connecting a batt to it, get the resistance as high as possible. Experiment with length.

It would seem that if you get the resistance high enough, but not too high, you can get a good feel for time vs temp.

Well, i have experience using nichrome wire in my ecig. I have several juice tanks that use a coil of nichrome wrapped around silica wick. IIRC, the higher the guage, the lower the resistance per foot. I would say try getting the thinnest possible, and wrap alot around. Since you are basically connecting a batt to it, get the resistance as high as possible. Experiment with length.

It would seem that if you get the resistance high enough, but not too high, you can get a good feel for time vs temp.

At with a 3.7v average you can only use at most around 3 inches of wire for it to heat effectively. anything past that it barley gets warm. I was able to wrap it around 1.5 times. I should of used 40awg also maybe use a boost circuit to allow me to use a longer piece of wire

At with a 3.7v average you can only use at most around 3 inches of wire for it to heat effectively. anything past that it barley gets warm. I was able to wrap it around 1.5 times. I should of used 40awg also maybe use a boost circuit to allow me to use a longer piece of wire

Wow, nice link, thanks! Never thought to look for a calc, just tried what most others did.

The 40 guage would probably let you get a little more around it. Have you looked into kanthal wire? Thats another popular heating element in ecigs, i personal don't like it. I won't say for certain, but i think it has a lower resistance. I made one coil with some 32 guage, biggest coil i ever made, had the lowest resistance too. It might work better than the nichrome.

As for the circuit, maybe several coils in parallel to get more spred.

Wow, nice link, thanks! Never thought to look for a calc, just tried what most others did.

The 40 guage would probably let you get a little more around it. Have you looked into kanthal wire? Thats another popular heating element in ecigs, i personal don't like it. I won't say for certain, but i think it has a lower resistance. I made one coil with some 32 guage, biggest coil i ever made, had the lowest resistance too. It might work better than the nichrome.

As for the circuit, maybe several coils in parallel to get more spred.

Or you could use a thermistor to control it...

I'll look into that wire.

Didn't think about messing around with parallel circuits. But for nichrome I am going to to find someway to get a higher voltage from a 3.7v. But say I run 3 x 3" parallel voltage stays the same for each one.... so I need a battery capable of some major current glad I already have panasonic ncr18650pd's in the mail.

I was up in the air between using a rheostat or setting up a 555 timer circuit that will just keep switching on and off. I make these already for oxygen sensor simulators but that is only switching between 0 and .7-.9v

did you see the other use i found for nichrome wire besides lighting fuses!

You might want to try a PTC-Positive Temperature Coefficient-thermistor either to control current to the nichrome wire, or even better, to replace it. PTC thermistors have low resistance when cold. The higher the temperature gets the higher their resistance. You could use some thermal epoxy to secure one or more small ones to your green module. As the module warms up the resistance of these thermistors would go up lowering the amount of heat being generated. Of course a PL520 would be the most elegant solution 8-)

Thanks for the link, I hadn't seen it. Actually, i never really thought about how useful it could be

They have dual coil carts with the ecig that put two high ohm coils in parallel, dropping total resistance. I've seen carts with two 5 ohm coils in parallel, making total resistance 2.5 ohm. They need about 5 - 6v to run good.

As far as power goes, IMR batts all the way. According to the spec, an AW IMR 18650 is capable of supplying 16A for ten min. These batts are all about high current drain.

You might want to try a PTC-Positive Temperature Coefficient-thermistor either to control current to the nichrome wire, or even better, to replace it. PTC thermistors have low resistance when cold. The higher the temperature gets the higher their resistance. You could use some thermal epoxy to secure one or more small ones to your green module. As the module warms up the resistance of these thermistors would go up lowering the amount of heat being generated. Of course a PL520 would be the most elegant solution 8-)

Thanks for the info I got even more options to research now lol. And I don't know how the 520 will hold up on a gun.... I don't want to kill my $145 diode after 10 shots

Quote:

Originally Posted by ChaosLord

Thanks for the link, I hadn't seen it. Actually, i never really thought about how useful it could be

They have dual coil carts with the ecig that put two high ohm coils in parallel, dropping total resistance. I've seen carts with two 5 ohm coils in parallel, making total resistance 2.5 ohm. They need about 5 - 6v to run good.

As far as power goes, IMR batts all the way. According to the spec, an AW IMR 18650 is capable of supplying 16A for ten min. These batts are all about high current drain.